#main {
    position: fixed;
    width: 100%;
    height: 100%;
}
#main img{
    width: 100%;
    height: 100%;
}
h1{
    position: absolute;
    width: 100%;
    top:30px;
    color:white ;
    text-align: center;
}
h2{
    position: absolute;
    width: 100%;
    top:60px;
    color:white ;
    text-align: center;
}
.erweima {
    position: absolute;
    width:200px;
    height: 200px;
    top:100px;
    background: white;
    left:50%;
    margin-left: -100px;
    box-sizing: border-box;
    padding: 10px;
}
.bot{
    position: absolute;
    top:350px;
    font-size: 0.7rem;
    color: white;
    width: 90%;
    left:5%;
   background: rgba(255,255,255,.2);
    padding: 15px 10px;
    box-sizing: border-box;
    line-height: 150%;
}